Electricity + Control January 2016

ENERGY + ENVIROFICIENCY: FOCUS ON STANDBY + BACK-UP

to high pressure fuel systems and prognostic capabilities are other improvements that lead to operating cost reductions.

rings and hardened cylinder features, together with enhanced piston cooling, reduce piston ring temperatures and increase wear resistance and cylinder life. This reduces total lifecycle costs.

Conclusion The rise of distributed generation through decentralised power supply schemes is further evolving. Decentralisation is not just about displace- ment of grid power with one energy source, but how to optimise de- centralised systems with various fuel sources for objectives of energy efficiency, reliability and critical process protection. A typical scheme could comprise renewable power generation sources such as wind and solar but these pose challenges to system reliability and perfor- mance, given their inherent intermittent contribution and associated disturbances. Gas to power programmes in Southern Africa are

Efficiency Efficiency in a diesel engine is most directly tied to combustion rate, the degree to which the fuel is completely burned during ignition. This is typically a function of how finely and evenly dispersed the fuel is during injection into the combustion chamber. Turbocharging, which forces excess air into the chamber, also improves combustion rate, which is why two-stage turbocharging (with intercooling between the stages) is now common for diesel gensets. Modular Common Rail System (MCRS) enables diesel engines to achieve exceptionally low fuel consumption for its power output. The MCRS injectors are capable of extremely high pressure injection that leads to a reduction in particulate matter emissions. This method replaces traditional mechanical injec- tion with electronically controlled multiple high- pressure injections during each combustion cycle. Rather than rely on separate injectors controlled by a camshaft, it uses a single system that supplies all the injectors in the engine with a common source of fuel. This allows much higher fuel pressures than a mechanical injection system, which maximises vaporisation of the fuel and thus, combustion rate. Modern high-pressure common-rail diesel fuel systems allow for much higher fuel pressures andmuchmore precise and flexible injection of fuel into the combustion chamber. To meet Tier 4, the strictest emission Selective Catalytic Reduction (SCR) has been successfully used on new diesel gensets to reduce NOx emissions as much as 95%. Another method often usedwith it is exhaust gas recircu- lation, which sends part of the exhaust gases back into the combustion chamber. This lowers the adiabatic flame temperature, allowing for lower-temperature combustion and thus lower NOx production. The use of SCR also enables 5% more fuel efficiency. Digital controls Digital controls are essential for the newest gensets that rely on high pressure common rail injection fuel injection systems and precise control of ignition and combustion. They are also necessary where tight emissions compliance is a consideration. Another advantage is that digital controls can monitor the real-time state of a wide variety of operating parameters and display them on a centralised panel, as opposed to analogue systems that are less sophisticated. This allows operators to identify and correct faults much more quickly, leading to more reliable power and less downtime. They also allow for remote monitoring and operation. With diesel gensets typically representing either emergency generation or generation where there may be no grid power to fall back on, these are critical considerations. Oil management systems that automatically replenish oil based on engine-load factors, fuel filtrations systems with enhanced durability

yet to overcome challenges such as pipeline natural gas infrastructure and moderating market price. Diesel engine power plants have synchronous technology and contribute a high level of operational stabil- ity for standby or prime power applications together withmature diesel fuel supply chains. Manufacturers of diesel gensets are making steady technology gains that reduce capital in- tensity and emission levels and enhance power output and efficiency. Diesel generated power is still likely to feature on its own or incorporated into hybrid solutions for many more years.

References [1] OvertonTW.2015.DieselGensetsAimattheFuture.PowerMagazine. [2] Natekar A and Menzel M. 2010. The Impact of Tier 4 Emission Regulations on the Power Generation Industry. Power Topic #9010 Technical Information from Cummins Power Generation.

• Even diesel generator technology is evolving. • Specific effort is being placed on reducing the carbon footprint of diesel plants. • The trend is to combine diesel and alternative energy sources.

take note

Nalen Alwar holds a Master’s Degree in Business Admin- istration and a Bachelor’s Degree in Chemical Engineering Technology. He has 12 years of senior management experi- ence in the areas of Strategic Business Development, Sales, Key Accounts Management, Supply Chain Management and Process Operations. He has been working in the power industry for the past four years and is currently employed as the Projects Sales Manager for Cummins Power Generation in Southern Africa. Enquiries: Tel. 011 321 8700 or email nalen.alwar@cummins.com

Electricity+Control January ‘16

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